This is certainly a value judgment, but it strikes me as foolish to be in Atlanta and discount DL (and the SkyTeam alliance). Delta's the hometown airline in the world's largest airport hub. DL is the #1 carrier across the Atlantic (although I'm not sure if that's number of flights rather than # of seats or revenue passenger miles).

The OP should ask himself why he wants to fly a foreign carrier. Really think that Iberia, AF or Alitalia (Ha!) is better than Delta in coach?

The frequency and diversity of flights from ATL plus the expansion of international service from JFK makes this an easy choice.